Breast cancer in men accounts for about 1% of all breast cancers and about 0.2% of all cancers in men. There will be about 1,690 new cases of male breast cancer in 2005, compared to 213,000 cases in women. Risk factors for the development of male breast cancer include Klinefelter's syndrome, being of Jewish descent, mumps orchitis, a family history of male or female breast cancer and family cancer syndromes (BRCA1 & 2 gene abnormalities account for 40% of cases).

The predominant presenting symptom is a mass in the breast. Other symptoms and signs of male breast cancer include nipple discharge (particularly if bloody), nipple retraction and skin ulceration. Mammograms are difficult to perform, particularly on thin men, so a biopsy should be done on a suspicious lump.

The treatment of male breast cancer is similar to that of female breast cancer. Historically, radical mastectomy was the treatment of choice, but surgeons may perform less aggressive surgery if the cancer is small and doesn't involve underlying chest muscle. The use of radiation, chemotherapy and hormone therapy (tamoxifen) after surgical removal of the tumor follows the same principles as in female breast cancer.